The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems are used to deposit and etch film on a substrate. For example for the substrate processing system may perform chemical vapor deposition (CVD), plasma-enhanced (PE) CVD, atomic layer deposition (ALD), PEALD, etc. Deposition and/or etching may be performed by supplying a gas mixture to a processing chamber. The gas mixture may include one or more gases that are mixed together. In some situations, one or more of the gases may be generated from a liquid precursor that is vaporized. Precise metering of the liquid precursor is performed to ensure that the correct gas mixture is formed in the processing chamber.
Thermal or Coriolis flow controllers are typically used to meter the liquid precursor flowing to the vaporizer. Liquid flow controllers are fully opened until a metering tube is filled. As a result, the liquid flow controllers typically overshoot a desired flow rate. In these types of systems, settling time for the flow rate can be greater than 10 seconds. Some substrate processing systems with long settling times divert the liquid or vaporized precursor until liquid flow is stabilized. Occasionally, a bubble will become trapped in the metering tube and inaccurate or no flow will persist until the liquid delivery system is serviced.